72 ILLINOIS BIOLOGICAL MONOGRAPHS [282 



STENOPHORA LACTARIA Watson 

 [Figure 55] 

 1915 Stenophora lactaria Watson 1915 :29-30 



A gregarine which was found with relative frequency is this one 

 from the intestinal tract of the small diplopod Callipus lactarius (Say), 

 taken at Urbana, Illinois, during the month of October, 1914. The infec- 

 tion per host was heavy and sections of the alimentary tract showed the 

 latter half of the same to be heavily parasitised. 



A table of various dimensions of the parasites at different ages fol- 

 lows. There is considerable discrepancy in the ratios given but the fact 

 that there is a gradual transition from one extreme to the other indi- 

 cates that a single species is involved. Measurements were made only 

 of individuals which to all appearances were equally expanded; dimen- 

 sions are all given in microns : 



Total length sporont 175 216 293 304 339 455 480 



Length protomerite 28 27 30 30 20 36 30 



Length deutomerite 145 189 213 264 319 419 450 



Width protomerite 30 30 39 29 39 35 39 



Width deutomerite 54 53 90 61 90 65 90 



Ratio 



length protom. : tl. length.! :6 1 :7.5 1 :10 1 :10 1 :17 1 :13 1 :16 



width prot. : width deutl :1. 8 1:1.8 1:2.3 1:2.1 1:2.3 1:1.9 1:2.3 

 The sporonts, as in all members of this family, are solitary until just 

 previous to cyst formation. The body, when moderately expanded, is 

 shaped like a classic vase, widest near the top and tapering very grad- 

 ually. The protomerite is small in comparison with the deutomerite, be- 

 ing from one eighth (in young specimens) to one sixteenth the total 

 length. It is conical, widest just anterior to the base, and its breadth ex- 

 ceeds its height. (39 by 30/^; 32 by 29/x). It is from 0.4 to 0.6 as wide 

 as the deutomerite at its widest part. There is a slight invagination at 

 the anterior end. The deutomerite is widest a short distance below the 

 conscription at the septum and tapers gradually toward the posterior 

 end, terminating in a blunt cone. 



The protomerite is quite or nearly transparent, containing but few 

 large crystal granules of protoplasm which stain deeply. There is an ap- 

 parent pore at the anterior end. The deutomerite is more or less dense 

 and opaque, being pearly white in reflected light and light or dark gray, 

 depending on the amount of protoplasm present, in transmitted light. 

 The density depends on age, the young trophozoites containing a few 

 pale gray granules, the oldest and largest sporonts being filled with pro- 



